Ray's Knowledge Basehttps://rkb.rs.ht/Pitfalls with their fixes, recipes, facts and decisions from real work.`Series::flat(TypeId::Bool, ...)` returns an empty Serieshttps://rkb.rs.ht/projects/dftracer-utils/dataframe/series-flat-typeid-bool-returns-an-empty-series/https://rkb.rs.ht/lessons/a681fe7dee/Mon, 28 Sep 2026 00:00:00 +0000`StringViewSet` owns its strings, so views into a temporary one danglehttps://rkb.rs.ht/projects/dftracer-utils/dataframe/stringviewset-owns-its-strings-so-views-into-a-temporary-one/https://rkb.rs.ht/lessons/acf2416942/Mon, 28 Sep 2026 00:00:00 +0000A large clap derive command tree overflows the 2 MiB stack of test threads in debug buildshttps://rkb.rs.ht/general/rust/a-large-clap-derive-command-tree-overflows-the-2-mib-stack/https://rkb.rs.ht/lessons/12909da5c5/Mon, 28 Sep 2026 00:00:00 +0000A range-for over a member of a temporary reads freed memoryhttps://rkb.rs.ht/general/cpp/a-range-for-over-a-member-of-a-temporary-reads-freed-memory/https://rkb.rs.ht/lessons/94296edbdb/Mon, 28 Sep 2026 00:00:00 +0000A raw string literal ends at the first `)"`, even inside a quoted patternhttps://rkb.rs.ht/general/cpp/a-raw-string-literal-ends-at-the-first-even-inside-a-quoted/https://rkb.rs.ht/lessons/5c3ddcf86b/Mon, 28 Sep 2026 00:00:00 +0000After libgit2 rewrites the index, git status can miss a same-second, same-size edithttps://rkb.rs.ht/general/git/after-libgit2-rewrites-the-index-git-status-can-miss-a-same/https://rkb.rs.ht/lessons/d6c672dab8/Mon, 28 Sep 2026 00:00:00 +0000After rgit stage --hunk, check the index before committinghttps://rkb.rs.ht/general/git/after-rgit-stage-hunk-check-the-index/https://rkb.rs.ht/lessons/5f0ebe448c/Mon, 28 Sep 2026 00:00:00 +0000Build a ground-truth set for PDF extraction from arXiv LaTeX sourceshttps://rkb.rs.ht/general/testing/build-a-ground-truth-set-for-pdf-extraction-from-arxiv-latex/https://rkb.rs.ht/lessons/1aedf6a93e/Mon, 28 Sep 2026 00:00:00 +0000Build PCRE2 as a static 8-bit library with JIT through CPMhttps://rkb.rs.ht/general/cmake/build-pcre2-as-a-static-8-bit-library-with-jit-through-cpm/https://rkb.rs.ht/lessons/6007cb5ea3/Mon, 28 Sep 2026 00:00:00 +0000candle-core 0.10 and later always pull in tokenizers and the Oniguruma C libraryhttps://rkb.rs.ht/general/candle/candle-core-0-10-and-later-always-pull-in-tokenizers-and-the/https://rkb.rs.ht/lessons/335a071882/Mon, 28 Sep 2026 00:00:00 +0000Clang calls `this` unused in a generic lambda that calls a member without `this->`https://rkb.rs.ht/general/cpp/clang-calls-this-unused-in-a-generic-lambda-that-calls-a/https://rkb.rs.ht/lessons/9caab93e76/Mon, 28 Sep 2026 00:00:00 +0000granite-docling-258M runs at about 1 token per second through transformers on Apple Siliconhttps://rkb.rs.ht/general/python/granite-docling-258m-runs-at-about-1-token-per-second/https://rkb.rs.ht/lessons/e6196732a5/Mon, 28 Sep 2026 00:00:00 +0000How git's octopus merge works, for a tool that must match ithttps://rkb.rs.ht/general/git/how-git-s-octopus-merge-works-for-a-tool-that-must-match-it/https://rkb.rs.ht/lessons/e238d3e4e6/Mon, 28 Sep 2026 00:00:00 +0000libgit2 applies a hunk at its new-side start line, so a hand-built one-hunk patch needs that line on the + sidehttps://rkb.rs.ht/general/git/libgit2-applies-a-hunk-at-its-new-side-start-line-so-a-hand/https://rkb.rs.ht/lessons/bfb11a3684/Mon, 28 Sep 2026 00:00:00 +0000libgit2 ignores GIT_CONFIG_GLOBAL and still reads ~/.gitconfig and ~/.config/git/confighttps://rkb.rs.ht/general/git/libgit2-ignores-git-config-global-and-still-reads-gitconfig/https://rkb.rs.ht/lessons/2b214bbe4e/Mon, 28 Sep 2026 00:00:00 +0000libgit2's cleanup_state also deletes BISECT_LOG, which breaks a bisect in progresshttps://rkb.rs.ht/general/git/libgit2-s-cleanup-state-also-deletes-bisect-log-which-breaks/https://rkb.rs.ht/lessons/70463c8ef2/Mon, 28 Sep 2026 00:00:00 +0000pdftotext -bbox-layout splits small caps, section numbers and captions in ways a parser must undohttps://rkb.rs.ht/general/pdf/pdftotext-bbox-layout-splits-small-caps-section-numbers-and/https://rkb.rs.ht/lessons/cfcebd5094/Mon, 28 Sep 2026 00:00:00 +0000Pruning must key a literal the way the index stored the valuehttps://rkb.rs.ht/general/index/pruning-must-key-a-literal-the-way-the-index-stored-the/https://rkb.rs.ht/lessons/460f1b1259/Mon, 28 Sep 2026 00:00:00 +0000rait finds PDF tables with Table Transformer in Rust, and word positions fill the cellshttps://rkb.rs.ht/projects/rait/pdf/rait-finds-pdf-tables-with-table-transformer-in-rust-and/https://rkb.rs.ht/lessons/29162278af/Mon, 28 Sep 2026 00:00:00 +0000rait prefers pure-Rust crates and allows C only where no good Rust option existshttps://rkb.rs.ht/projects/rait/rust/rait-prefers-pure-rust-crates-and-allows-c-only-where-no/https://rkb.rs.ht/lessons/6b8c4f5169/Mon, 28 Sep 2026 00:00:00 +0000rait's held-out PDF evaluation set: 12 arXiv papers and the scores to beathttps://rkb.rs.ht/projects/rait/testing/rait-s-held-out-pdf-evaluation-set-12-arxiv-papers-and-the/https://rkb.rs.ht/lessons/7729befd86/Mon, 28 Sep 2026 00:00:00 +0000rgit stage --hunk reports success for a hunk it did not stagehttps://rkb.rs.ht/projects/rgit/staging/rgit-stage-hunk-reports-success-for-a-hunk-it-did-not-stage/https://rkb.rs.ht/lessons/f96b3b5f31/Mon, 28 Sep 2026 00:00:00 +0000Run many coding agents on one Rust repository without overloading the machinehttps://rkb.rs.ht/general/agents/run-many-coding-agents-on-one-rust-repository-without/https://rkb.rs.ht/lessons/fdcb6e487f/Mon, 28 Sep 2026 00:00:00 +0000Stale gcov data makes tests crash at exit after a rebuildhttps://rkb.rs.ht/general/testing/stale-gcov-data-makes-tests-crash-at-exit-after-a-rebuild/https://rkb.rs.ht/lessons/7f64922551/Mon, 28 Sep 2026 00:00:00 +0000Table Transformer structure recognition misreads small tables that are scaled up to 800 pxhttps://rkb.rs.ht/general/pdf/table-transformer-structure-recognition-misreads-small/https://rkb.rs.ht/lessons/ff383d4e63/Mon, 28 Sep 2026 00:00:00 +0000transformers 5 refuses the Table Transformer v1.1 config because `dilation` is nullhttps://rkb.rs.ht/general/python/transformers-5-refuses-the-table-transformer-v1-1-config/https://rkb.rs.ht/lessons/7844ab3958/Mon, 28 Sep 2026 00:00:00 +0000Twin-repo git comparisons flake unless every commit has a fixed date and asserts match whole tokenshttps://rkb.rs.ht/general/testing/twin-repo-git-comparisons-flake-unless-every-commit-has-a/https://rkb.rs.ht/lessons/52a9cd1bf9/Mon, 28 Sep 2026 00:00:00 +0000zsh does not split an unquoted variable into words, unlike bashhttps://rkb.rs.ht/general/shell/zsh-does-not-split-an-unquoted-variable-into-words-unlike/https://rkb.rs.ht/lessons/777c0fa71d/Mon, 28 Sep 2026 00:00:00 +0000`??` followed by `'`, `(`, `)` and others in a C++ string is a trigraphhttps://rkb.rs.ht/general/cpp/followed-by-and-others-in-a-c-string-is-a-trigraph/https://rkb.rs.ht/lessons/43fa6590da/Sun, 27 Sep 2026 00:00:00 +0000`[[maybe_unused]]` on one structured binding name is a C++26 extensionhttps://rkb.rs.ht/general/cpp/maybe-unused-on-one-structured-binding-name-is-a-c-26/https://rkb.rs.ht/lessons/77de813d2a/Sun, 27 Sep 2026 00:00:00 +0000`doxygen docs/Doxyfile` from the repo root writes a stray `doxygen/` folderhttps://rkb.rs.ht/projects/dftracer-utils/docs/doxygen-docs-doxyfile-from-the-repo-root-writes-a-stray/https://rkb.rs.ht/lessons/4b6d101280/Sun, 27 Sep 2026 00:00:00 +0000`PyObject_IsTrue(v) > 0 ? true : fallback` turns False into the defaulthttps://rkb.rs.ht/general/python/pyobject-istrue-v-0-true-fallback-turns-false-into-the/https://rkb.rs.ht/lessons/92a77ef537/Sun, 27 Sep 2026 00:00:00 +0000A byte pre-filter on JSON lines must not assume how the writer spelled the JSONhttps://rkb.rs.ht/general/json/a-byte-pre-filter-on-json-lines-must-not-assume-how-the/https://rkb.rs.ht/lessons/dabf49f344/Sun, 27 Sep 2026 00:00:00 +0000A consumer that stops reading a bounded channel on error leaves its producers blocked foreverhttps://rkb.rs.ht/general/cpp/a-consumer-that-stops-reading-a-bounded-channel-on-error/https://rkb.rs.ht/lessons/a022984789/Sun, 27 Sep 2026 00:00:00 +0000A false `[ ... ] && cmd` as the last command of a shell case branch makes the script exit 1https://rkb.rs.ht/general/shell/a-false-cmd-as-the-last-command-of-a-shell-case-branch-makes/https://rkb.rs.ht/lessons/a2733919ad/Sun, 27 Sep 2026 00:00:00 +0000A new query leaf form must be handled in every place that reads query leaveshttps://rkb.rs.ht/projects/dftracer-utils/query/a-new-query-leaf-form-must-be-handled-in-every-place-that/https://rkb.rs.ht/lessons/8ebf78df23/Sun, 27 Sep 2026 00:00:00 +0000A test that shells out to a real CLI with side effects can change the user's real confighttps://rkb.rs.ht/general/testing/a-test-that-shells-out-to-a-real-cli-with-side-effects-can/https://rkb.rs.ht/lessons/fb8237851b/Sun, 27 Sep 2026 00:00:00 +0000A/B timings on a busy shared machine both hide and fake regressionshttps://rkb.rs.ht/general/testing/a-b-timings-on-a-busy-shared-machine-both-hide-and-fake/https://rkb.rs.ht/lessons/f1b7c08b8d/Sun, 27 Sep 2026 00:00:00 +0000Agents do not reliably load a skill, so must-follow rules need always-on context or toolshttps://rkb.rs.ht/general/agents/agents-do-not-reliably-load-a-skill-so-must-follow-rules/https://rkb.rs.ht/lessons/6342712def/Sun, 27 Sep 2026 00:00:00 +0000Agents reach rkb through tools: a Claude Code plugin with an MCP server, and a pi/omp extensionhttps://rkb.rs.ht/projects/rkb/integration/agents-reach-rkb-through-tools-a-claude-code-plugin-with-an/https://rkb.rs.ht/lessons/ffc37c3abe/Sun, 27 Sep 2026 00:00:00 +0000Aggregation tier state that spans builds and processeshttps://rkb.rs.ht/projects/dftracer-utils/index/aggregation-tier-state-that-spans-builds-and-processes/https://rkb.rs.ht/lessons/23cb9ddb24/Sun, 27 Sep 2026 00:00:00 +0000An index build after a tier-served query fails with "Cannot upgrade RocksDB instance"https://rkb.rs.ht/projects/dftracer-utils/index/an-index-build-after-a-tier-served-query-fails-with-cannot/https://rkb.rs.ht/lessons/692aa0f35b/Sun, 27 Sep 2026 00:00:00 +0000An unquoted `null` in a YAML list is a null, not the string "null"https://rkb.rs.ht/general/yaml/an-unquoted-null-in-a-yaml-list-is-a-null-not-the-string/https://rkb.rs.ht/lessons/a38845558b/Sun, 27 Sep 2026 00:00:00 +0000candle compiles Metal kernels on the first GPU run of each binaryhttps://rkb.rs.ht/general/candle/candle-compiles-metal-kernels-on-the-first-gpu-run-of-each/https://rkb.rs.ht/lessons/9bf54f7054/Sun, 27 Sep 2026 00:00:00 +0000Check a hand-written parser's grammar with a Lark LALR(1) copy and one shared sample filehttps://rkb.rs.ht/general/parsing/check-a-hand-written-parser-s-grammar-with-a-lark-lalr-1/https://rkb.rs.ht/lessons/f0aec3a6a8/Sun, 27 Sep 2026 00:00:00 +0000Claude Code plugins from a local marketplace: layout, updates, tool names and permissionshttps://rkb.rs.ht/general/claude-code/claude-code-plugins-from-a-local-marketplace-layout-updates/https://rkb.rs.ht/lessons/c5698e8ae2/Sun, 27 Sep 2026 00:00:00 +0000Code that assumes the dftracer schema breaks other record schemas silentlyhttps://rkb.rs.ht/projects/dftracer-utils/views/code-that-assumes-the-dftracer-schema-breaks-other-record/https://rkb.rs.ht/lessons/a4be58e760/Sun, 27 Sep 2026 00:00:00 +0000corfu's auto popup also opens in the minibuffer, including evil's `:` linehttps://rkb.rs.ht/general/emacs/corfu-s-auto-popup-also-opens-in-the-minibuffer-including/https://rkb.rs.ht/lessons/4f6f1844b5/Sun, 27 Sep 2026 00:00:00 +0000CTest tests that run a build in the build tree must share RESOURCE_LOCK build_treehttps://rkb.rs.ht/projects/dftracer-utils/testing/ctest-tests-that-run-a-build-in-the-build-tree-must-share/https://rkb.rs.ht/lessons/6a0bf5e312/Sun, 27 Sep 2026 00:00:00 +0000Delete exactly one key through a range-delete-only interfacehttps://rkb.rs.ht/general/rocksdb/delete-exactly-one-key-through-a-range-delete-only-interface/https://rkb.rs.ht/lessons/5b9a467811/Sun, 27 Sep 2026 00:00:00 +0000duql replaces dictionaries, resolved columns and the metadata phase with querieshttps://rkb.rs.ht/projects/dftracer-utils/query/duql-replaces-dictionaries-resolved-columns-and-the-metadata/https://rkb.rs.ht/lessons/9b33c983d4/Sun, 27 Sep 2026 00:00:00 +0000eglot freezes Emacs when a language server asks to watch files outside any version-control roothttps://rkb.rs.ht/general/emacs/eglot-freezes-emacs-when-a-language-server-asks-to-watch/https://rkb.rs.ht/lessons/081cbec6cd/Sun, 27 Sep 2026 00:00:00 +0000eglot inlay hints make cursor movement laggy in large files while the server is busyhttps://rkb.rs.ht/general/emacs/eglot-inlay-hints-make-cursor-movement-laggy-in-large-files/https://rkb.rs.ht/lessons/977650a9f3/Sun, 27 Sep 2026 00:00:00 +0000Emacs on macOS can only make the whole GUI frame see-through, not just its backgroundhttps://rkb.rs.ht/general/emacs/emacs-on-macos-can-only-make-the-whole-gui-frame-see-through/https://rkb.rs.ht/lessons/789b14cc9f/Sun, 27 Sep 2026 00:00:00 +0000evil-collection binds SPC in many modes, which hides a global SPC leaderhttps://rkb.rs.ht/general/emacs/evil-collection-binds-spc-in-many-modes-which-hides-a-global/https://rkb.rs.ht/lessons/0704c3593f/Sun, 27 Sep 2026 00:00:00 +0000For design questions, research and discuss first; new dependencies are fine when they win on performancehttps://rkb.rs.ht/projects/dftracer-utils/workflow/for-design-questions-research-and-discuss-first-new/https://rkb.rs.ht/lessons/9ed10f34db/Sun, 27 Sep 2026 00:00:00 +0000How today's filter language treats missing fields, null, types and patternshttps://rkb.rs.ht/projects/dftracer-utils/query/how-today-s-filter-language-treats-missing-fields-null-types/https://rkb.rs.ht/lessons/54489520b7/Sun, 27 Sep 2026 00:00:00 +0000Laya asks whether the lesson is about the same problem, not whether it helpshttps://rkb.rs.ht/projects/rkb/rerank/laya-asks-whether-the-lesson-is-about-the-same-problem-not/https://rkb.rs.ht/lessons/173a08ddf5/Sun, 27 Sep 2026 00:00:00 +0000libdeflate cannot recover a cut gzip member, so decode the last member with zlib streaminghttps://rkb.rs.ht/general/gzip/libdeflate-cannot-recover-a-cut-gzip-member-so-decode-the/https://rkb.rs.ht/lessons/2384fc588f/Sun, 27 Sep 2026 00:00:00 +0000Many small parallel Accelerate sgemm calls are slower than one large callhttps://rkb.rs.ht/general/macos/many-small-parallel-accelerate-sgemm-calls-are-slower-than/https://rkb.rs.ht/lessons/fe20188ecd/Sun, 27 Sep 2026 00:00:00 +0000Never search the whole disk from the root folderhttps://rkb.rs.ht/general/agents/never-search-the-whole-disk-from-the-root-folder/https://rkb.rs.ht/lessons/7025a6f105/Sun, 27 Sep 2026 00:00:00 +0000On macOS the first GUI frame of an Emacs daemon turns the menu bar back on in terminal frameshttps://rkb.rs.ht/general/emacs/on-macos-the-first-gui-frame-of-an-emacs-daemon-turns-the/https://rkb.rs.ht/lessons/bd6003ecb8/Sun, 27 Sep 2026 00:00:00 +0000pi and omp extension events for compaction, shutdown and commandshttps://rkb.rs.ht/general/pi/pi-and-omp-extension-events-for-compaction-shutdown-and/https://rkb.rs.ht/lessons/9fc423871b/Sun, 27 Sep 2026 00:00:00 +0000Pruning evidence is sound only for the records it was built fromhttps://rkb.rs.ht/general/index/pruning-evidence-is-sound-only-for-the-records-it-was-built/https://rkb.rs.ht/lessons/cf0e3f44ea/Sun, 27 Sep 2026 00:00:00 +0000Recall adds only a clear top lesson: relevance 0.85 and 0.10 above the nexthttps://rkb.rs.ht/projects/rkb/rerank/recall-adds-only-a-clear-top-lesson-relevance-0-85-and-0-05/https://rkb.rs.ht/lessons/d78a61f8ee/Sun, 27 Sep 2026 00:00:00 +0000Record the old parser's output over every in-repo query before replacing the parserhttps://rkb.rs.ht/general/testing/record-the-old-parser-s-output-over-every-in-repo-query/https://rkb.rs.ht/lessons/f561225b35/Sun, 27 Sep 2026 00:00:00 +0000rkb captures sessions on signals and distills only when asked, with no model of its ownhttps://rkb.rs.ht/projects/rkb/distill/rkb-captures-sessions-on-signals-and-distills-only-when/https://rkb.rs.ht/lessons/9e1bf57e4e/Sun, 27 Sep 2026 00:00:00 +0000rkb prints human text by default, and agents pass --toonhttps://rkb.rs.ht/projects/rkb/output/rkb-prints-human-text-by-default-and-agents-pass-toon/https://rkb.rs.ht/lessons/42b86937f2/Sun, 27 Sep 2026 00:00:00 +0000Run the Python suite and the docs build without installing anythinghttps://rkb.rs.ht/projects/dftracer-utils/testing/run-the-python-suite-and-the-docs-build-without-installing/https://rkb.rs.ht/lessons/6d925df652/Sun, 27 Sep 2026 00:00:00 +0000The aggregation tier holds no file id, so one file's rows cannot be replacedhttps://rkb.rs.ht/projects/dftracer-utils/index/the-aggregation-tier-holds-no-file-id-so-one-file-s-rows/https://rkb.rs.ht/lessons/9fd30501a4/Sun, 27 Sep 2026 00:00:00 +0000The query cache lives beside the index in `.dftindex-cache`, not inside `.dftindex`https://rkb.rs.ht/projects/dftracer-utils/index/the-query-cache-lives-beside-the-index-in-dftindex-cache-not/https://rkb.rs.ht/lessons/b892453993/Sun, 27 Sep 2026 00:00:00 +0000The Rust MCP crates all depend on Tokiohttps://rkb.rs.ht/general/rust/the-rust-mcp-crates-all-depend-on-tokio/https://rkb.rs.ht/lessons/3da7c59efe/Sun, 27 Sep 2026 00:00:00 +0000Time two builds with one scratch program, using the build's own compile and link lineshttps://rkb.rs.ht/general/testing/time-two-builds-with-one-scratch-program-using-the-build-s/https://rkb.rs.ht/lessons/85d6166574/Sun, 27 Sep 2026 00:00:00 +0000Typed record decode got 35% slower until per-leaf work left the hot loophttps://rkb.rs.ht/projects/dftracer-utils/views/typed-record-decode-got-35-slower-until-per-leaf-work-left/https://rkb.rs.ht/lessons/17df0d8e4a/Sun, 27 Sep 2026 00:00:00 +0000Which `(void)` casts may stay in dftracer-utilshttps://rkb.rs.ht/projects/dftracer-utils/code-style/which-void-casts-may-stay-in-dftracer-utils/https://rkb.rs.ht/lessons/030a9eb845/Sun, 27 Sep 2026 00:00:00 +0000Which View reads return dftracer metadata recordshttps://rkb.rs.ht/projects/dftracer-utils/views/which-view-reads-return-dftracer-metadata-records/https://rkb.rs.ht/lessons/09b402c770/Sun, 27 Sep 2026 00:00:00 +0000With rebase.updateRefs on, a backup branch made before a rebase does not keep the old historyhttps://rkb.rs.ht/general/git/with-rebase-updaterefs-on-a-backup-branch-made-before-a/https://rkb.rs.ht/lessons/a6296dd9db/Sun, 27 Sep 2026 00:00:00 +0000